The mountain is regarded as a forbidden and sacred place; one that holds a secret that the adults of Serene Village seem to be aware of, but refuse to elaborate on when asked. In order to prevent anyone from reaching the peak, the Serene Village adults and several others take turns on guard duty at several gates on the mountain.
At the peak, there is a spring filled with Luminous Water, which is able to reverse the effects of Pokémon being turned to stone. In addition to the villagers' security, the spring is protected by a barrier, which can only be broken by a Pokémon that came from the human world. The spring's presence is not spoken of in order to keep it a secret from evil.
First Expedition
As days continue to pass by with no sign that the player's memories are returning, Nuzleaf gets the idea to visit Revelation Mountain. He calls the player and the partner aside to tell them that he wants to secretly climb the mountain. Though the partner is shocked by this idea, he explains that he believes that the mountain may be linked to why the player was turned into a Pokémon. With a guarantee that they'll turn back if things become too difficult, the player and partner agree to join him.
At the entrance gate, they find that Hippopotas is on guard duty that day. After explaining the adults' guard duty schedule to the player and partner, Nuzleaf walks up to Hippopotas and tells him that there was a "mistake in guard duty", which Hippopotas buys and happily walks off, giving the group access to the mountain.
After scaling half of the mountain, the trio come across another gate, guarded by a Poliwrath, officers Magnemite, Magneton, and Magnezone, and a Beedrill. The group determines that it would be pointless to try to fight their way through, and decide to turn back. Since no answers were obtained concerning the player's memories, they deem the expedition a failure.
Second Expedition
Later, during the events of Chapter 16, once the player, partner, and Archen arrive at Serene Village and are greeted by Espurr, they encounter Nuzleaf rushing into the village. He claims that a Pokémon he had never seen before easily broke through his security at Revelation Mountain, and that he came to the village to find others to help stop the invader. After Nuzleaf describes the Pokémon in question, the group identifies it as Krookodile. As the group heads toward the mountain, Espurr offers the player and partner her assistance. However, the partner refuses by saying that Krookodile is a rather tough enemy, and instead tells her to warn Ampharos if they fail to return from Revelation Mountain. With that, the four head off to the entrance gate. As they hurry to the entrance, Nuzleaf mentions that there is a zealously-guarded secret of the mountain to Archen, leading the group to speculate that Krookodile might be after that secret.
Once they arrive and begin to climb the mountain, they find that the security gates have been destroyed and that the remaining guards were easily defeated. Later, between 10F and 11F, Archen and the player are contacted by Dedenne's team, who have been researching the Prehistoric Ruins. After Archen briefly tells her what they're doing, Dedenne replies that things are going rather well on their end, with Bunnelby having just discovered something. However, Dedenne and their crew's communication go dead due to being attacked by an unknown assailant. Although no one seems to know what has happened to them, Archen urges the team to move forward to the summit.
They reach the summit, and find no sign of Krookodile, but instead they see a spring surrounded by a mystic barrier. There's an ancient stone tablet which the partner is somehow able to read. It says "Should you hope to overcome this crisis, summon a person. A person will have the power to break the barrier over the spring. You must summon a person from the world of humans." They then get a call from Dedenne, saying that a special water called Luminous Water can bring Pokemon back from being turned to stone, and that it's there at Revelation Mountain. Krookodile then shows up, along with Raikou and Suicune, who intend to avenge Entei. Krookodile ignores them and continues to advance towards the group. Nuzleaf tells the hero they need to get the barrier broken now, before it's too late. After breaking the barrier, Nuzleaf is revealed to be the true villain behind turning Pokémon to stone. He proceeds to turn everyone else into stone with his dark power.
